Christina Applegate and Her Ex Smooch at L.A. Club

Christina Applegate and Johnathon Schaech's divorce was finalized in August, but the two apparently still have eyes for each other.

Applegate, 35, and Schaech, 38, ran into each other unexpectedly at L.A. hot spot Les Deux on Friday night – and ended up having a close encounter.

"They just made out all of a sudden," an observer tells PEOPLE. "They didn't really look around to see who was looking, it just happened, but it wasn't that weird after. They just went along talking to friends and separated soon after and both kept partying."

The flirty former couple were also seen holding hands, but they each ended the evening with their pals. Applegate, who stars in the new comedy series Samantha Who?, was hanging out with her girlfriends Eva Longoria and Sara Ramirez, while Schaech was with his actor friend Clifton Collins Jr.

Applegate and Schaech married in October 2001 and separated in December 2005. They have no children.

A rep for Applegate told PEOPLE: "I do not comment on clients' personal lives."